Most reciprocating piston internal combustion engines operate by converting heat and/or chemical energy into mechanical energy. Most of these internal combustion engines go through a series of processes known as thermodynamic cycles. Ideals thermodynamic cycles represent work input into a system, work gained from the system, and net work. Examining these ideal cycles shows certain inefficiencies.
In U.S. Pat. No. 3,623,463 issued to De Vries on Nov. 30, 1971, a system describes compressing and combusting an air fuel mixture in one cylinder and expanding and exhausting combustion gasses in a separate cylinder. This system effectively increases the expansion ratio of an engine by pairing a compression/combustion cylinder with an expansion/exhaust cylinder. In the limit these systems are called Atkinson cycle engines. These systems tend to increase engine size. Further, increased friction in a piston type engine may negate gains in efficiency.
In addition to increasing efficiencies, examination of the thermodynamic cycles shows that maximum power available from a given cycle depends on compression ratio instead of expansion ratio. For conventional engines, both expansion ratio and compression ratio are directly related to a cylinder bore and a piston stroke. In a typical four-cycle engine, the cylinder bore and the piston stroke remain constant during compression, expansion, exhaust, and induction cycles. U.S. Pat. No. 1,601,548 issued to Zier et al on Sep. 28, 1926 shows an engine having a compression cylinder having a larger bore taking in air on its down stroke and delivering compressed air to one of two smaller cylinders on its upward stroke. The two smaller cylinders are then used to combust, expand, and exhaust a fuel air mixture. A turbocharger may produce similar power results while reducing size and increasing efficiency relative to using a compression cylinder. However, turbochargers tend to require time for the engine to reach a certain speed before becoming effective. This problem is to referred to a turbo lag.
In an attempt to optimize both power and efficiency, U.S. Pat. No. 5,566,549 issued to Clarke on Oct. 22, 1996 shows an engine having a compression/induction cylinder, a combustion cylinder, and an expansion/exhaust cylinder. Both the compression/induction cylinder and the expansion/exhaust cylinder have larger bores than the combustion cylinder. This engine improves both efficiency and power. However, the increase in efficiency and power requires an increase in engine size. Typically, a user requires only greater efficiency or greater power but not both at the same time.
The present invention is directed to overcoming one or more of the problems set forth above.